Last major update issued on March 14, 2012 at 03:30 UTC.
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Annotated geomagnetic activity charts - Carrington rotation 2118 [December 2011 - January 2012] - 2119 [January-February 2012]
[Solar polar fields vs solar cycles - updated June 27, 2011]
The geomagnetic field was quiet to unsettled on March 13. Solar wind speed at SOHO ranged between 486 and 761 km/s under the influence of a CME.
Solar flux measured at 23h UTC on 2.8 GHz was 126.5 (increasing 21.9 over the last solar rotation, the observations at 17 and 20h UTC were flare enhanced). The planetary A index was 11 (STAR Ap - based on the mean of three hour interval ap indices: 11.4). Three hour interval K indices: 33212332 (planetary), 34323232 (Boulder).
The background x-ray flux is at the class B5 level.
At midnight UTC the visible solar disk had 6 spotted active regions (in 2K resolution SDO images).
Region 11429 [N18W66] decayed slowly and may be capable of producing
another major flare before rotating out of view. Flares:
C4.1 at 00:39, long duration C3.1 event peaking at 07:28, major long duration
M7.9 event peaking at 17:41 UTC. The latter event was associated with a
significant radiation storm and strong type II and IV radio bursts. A fast and
wide halo CME was observed as well.
Region 11432 [N15E14] was quiet and stable. Region S1525 to the southeast was split off.
Region 11433 [N13E37] developed further and has weak polarity intermixing. C flares and maybe a minor M class flare is possible. Flare: C1.2 at 01:50 UTC
Region 11434 [S22E30] decayed slowly and quietly.
Spotted regions not reported by NOAA/SWPC:
[S1524] emerged in the southeast quadrant on March 11. Location at midnight: S26E18
[S1525] was split off from region 11432 on March 13. Location at midnight: N13E17
March 13: The M7 event in region 11429 was associated with a halo CME
which could reach Earth on March 15.
March 11-12: No obviously Earth directed CMEs were observed in LASCO and STEREO imagery.
Coronal hole history (since October
Compare today's report to the situation one solar rotation ago: 28 days ago 27 days ago 26 days ago
A large recurrent trans equatorial coronal hole (CH507) was in an Earth facing position on March 13-14.
The above coronal hole map is based on a method where coronal holes are detected automatically. While the method may need some fine tuning, it has significant advantages over detecting coronal holes manually. The main improvement is the ability to detect coronal holes at and just beyond the solar limbs. Early results using this method for SDO images over a span of several weeks indicate a good match between coronal holes observed over the visible disk and their extent and position at the east and west limbs. Note that the polar coronal holes are easily detected using this method, the extent and intensity of both CHs are consistent with other data sources.
Long distance low and medium frequency (below 2 MHz) propagation along paths north of due west over high and upper middle latitudes is poor. Propagation on long distance northeast-southwest paths is fair.
The geomagnetic field is expected to be quiet to unsettled on March 14 due to lingering CME effects. On March 15 quiet to major storm conditions are likely as the CME observed on March 13 is expected to arrive. A high speed stream from CH507 in combination with the mentioned CME could cause unsettled to minor storm conditions on March 16-17
|Coronal holes (1)||Coronal mass ejections (2)||M and X class flares (3)|
1) Effects from a coronal hole could reach Earth within the
next 5 days. When the high speed stream has arrived the color changes to
2) Effects from a CME are likely to be observed at Earth within 96 hours.
3) There is a possibility of either M or X class flares within the next 48 hours.
Green: 0-20% probability, Yellow: 20-60% probability, Red: 60-100% probability.
Click on image for higher resolution image) Compare to the previous day's image
When available the active region map has a coronal hole polarity overlay where red (pink) is negative and blue (blue-green) is positive.
Data for all numbered solar regions according to the Solar Region Summary provided by NOAA/SWPC. Comments are my own, as is the STAR spot count (spots observed at or inside a few hours before midnight) and data for regions not numbered by SWPC or where SWPC has observed no spots. SWPC active region numbers in the table below and in the active region map above are the historic SWPC/USAF numbers.
|Active region||Date numbered
|Spot count||Location at midnight||Area||Classification||SDO / HMI 4K continuum
image with magnetic polarity overlay
|Total spot count:||30||78||38|
|Sunspot number:||80||138||98||(total spot count + 10 * number of spotted regions)|
|Weighted penumbral SN:||58||107||67||(Sum of total spot count + classification weighting for each AR. Classification weighting: X=0, R=3, A/S=5, H/K=10)|
|Relative sunspot number (Wolf number):||48||48||54||k * (sunspot number). k = 0.6 for SWPC, k = 0.35 (changed from 0.45 on March 1, 2011) for STAR SDO 2K, k = 0.55 for STAR SDO 1K|
|Month||Average measured solar flux||International sunspot number (SIDC)||Smoothed sunspot number||Average ap
|2008.07||65.7 (SF minimum)||0.5||2.8 (-0.4)|
|2010.12||84.2||14.4||28.8 (+2.3)||3.41 / 4.35|
|2011.01||83.6||19.1||31.0 (+2.2)||4.32 / 5.51|
|2011.02||94.6||29.4||33.4 (+2.4)||5.41 / 6.44|
|2011.03||115.0||56.2||36.9 (+3.5)||7.79 / 8.18|
|2011.04||112.6||54.4||41.8 (+4.9)||9.71 / 8.83|
|2011.05||95.8||41.6||47.6 (+5.8)||9.18 / 8.94|
|2011.06||95.8||37.0||53.2 (+5.6)||8.96 / 8.06|
|2011.07||94.2||43.9||57.2 (+4.0)||9.14 / 8.16|
|2011.08||101.7||50.6||59.0 (+1.8)||8.16 / 7.26|
|2011.09||133.8||78.0||(59.2 projected, +0.2)||12.80 / 12.27|
|2011.10||137.3||88.0||(59.4 projected, +0.2)||7.52 / 8.28|
|2011.11||153.5||96.7||(60.8 projected, +1.4)||4.58 / 5.55|
|2011.12||141.3||73.0||(63.6 projected, +2.8)||3.32|
|2012.01||132.5||58.3||(67.1 projected, +3.5)||6.59|
|2012.02||106.5||33.1||(71.0 projected, +3.9)||8.09|
|2012.03||127.9 (1)||33.2 (2A) / 79.2 (2B)||(73.2 projected, +2.2)||(25.13)|
1) Running average based on the daily 20:00 UTC observed solar flux value at
2A) Current impact on the monthly sunspot number based on the Boulder (NOAA/SWPC) sunspot number (accumulated daily sunspots / month days). The official SIDC international sunspot number is typically 30-50% lower. 2B) Month average to date.
3) Running average based on the preliminary daily SWPC ap indices. Values in red are based on the official NGDC ap indices.
This report has been prepared by Jan Alvestad. It is based on analysis of data from whatever sources are available at the time the report is prepared. All time references are to the UTC day. Comments and suggestions are always welcome.
SDO images are courtesy of NASA/SDO and the AIA, EVE, and HMI science teams.